// $Id: ConstraintDescriptor.java 17620 2009-10-04 19:19:28Z hardy.ferentschik $
/*
 * JBoss, Home of Professional Open Source
 * Copyright 2009, Red Hat, Inc. and/or its affiliates, and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package javax.validation.metadata;

import java.lang.annotation.Annotation;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.validation.ConstraintValidator;
import javax.validation.Payload;

/**
 * Describes a single constraint and its composing constraints. <code>T</code>
 * is the constraint's annotation type.
 *
 * @author Emmanuel Bernard
 * @author Hardy Ferentschik
 */
public interface ConstraintDescriptor<T extends Annotation> {
	/**
	 * Returns the annotation describing the constraint declaration. If a
	 * composing constraint, attribute values are reflecting the overridden
	 * attributes of the composing constraint
	 *
	 * @return The annotation for this constraint.
	 */
	T getAnnotation();

	/**
	 * The set of groups the constraint is applied on. If the constraint
	 * declares no group, a set with only the <code>Default</code> group is
	 * returned.
	 *
	 * @return The groups the constraint is applied on.
	 */
	Set<Class<?>> getGroups();

	/**
	 * The set of payload the constraint hosts.
	 *
	 * @return payload classes hosted on the constraint or an empty set if none.
	 */
	Set<Class<? extends Payload>> getPayload();

	/**
	 * List of the constraint validation implementation classes.
	 *
	 * @return list of the constraint validation implementation classes.
	 */
	List<Class<? extends ConstraintValidator<T, ?>>> getConstraintValidatorClasses();

	/**
	 * Returns a map containing the annotation attribute names as keys and the
	 * annotation attribute values as value. If this constraint is used as part
	 * of a composed constraint, attribute values are reflecting the overridden
	 * attribute of the composing constraint.
	 *
	 * @return a map containing the annotation attribute names as keys and the
	 *         annotation attribute values as value.
	 */
	Map<String, Object> getAttributes();

	/**
	 * Return a set of composing <code>ConstraintDescriptor</code>s where each
	 * descriptor describes a composing constraint.
	 * <code>ConstraintDescriptor</code> instances of composing constraints
	 * reflect overridden attribute values in {@link #getAttributes()} and
	 * {@link #getAnnotation()}.
	 *
	 * @return a set of <code>ConstraintDescriptor<code> objects or an empty set
	 *         in case there are no composing constraints.
	 */
	Set<ConstraintDescriptor<?>> getComposingConstraints();

	/**
	 * @return true if the constraint is annotated with
	 *         <code>@ReportAsSingleViolation</code>
	 */
	boolean isReportAsSingleViolation();
}
